Method of producing nickel powder from printing press plates and the like



March 1949. A. E. LUNDB YE 2,463,190

METHOD OF PRODUCING NICKEL POWDER FROM PRINTING PRESS PLATES AND THELIKE Filed July 1, 1946 WASH ELECTROLYTIC TANK TA NK INVENTOR. vA XEL E.LUNDB YE BY 841 mm M+Q A; ATTORNEYS.

Patented Mar. 1, 1949 UNITED STATES .P.

METHOD OF PRODUCING NICKEL POWDER FROM PRINTING PRESS PLATES AND THELIKE Axel E. Lundbye, North Pelham, N. Y., assignor to Crowell-CollierPublishing Company, Springfield, Ohio, a corporation of DelawareApplication July 1, 1946, Serial No. 680,7 90

5 Claims.

My invention relates to new and useful improvements in the method ofproducing nickel powder from reclaimed scrap in which nickel is one ofthe elements.

The present application is a continuation-inpart of application SerialNo. 447,582, filed June 18, 1942, now abandoned, and a companion to anapplication filed by me on May 23, 1942, bearing Serial No. 444,228, andentitled Method of and apparatus for the separation and reclamation ofcopper from printing plates and the like, now Patent No, 2,356,329,dated August 29, 1944, wherein the recovery of nickel was mentioned andwherein the invention was directed more specifically to the recovery ofcopper.

As is Well known to those skilled in the art, the letter press platesused in the large printing establishments are made up of a base metal,which is an alloy of lead, tin and antimony, which in turn has been caston a copper plate, which copper plate in turn has been electrolyticallydeposited on a layer of nickel.

Stating it in another manner, in making up these printing plates, theoriginal copper etching is pressed against a mold of lead. or wax whichmold is then electroplated with a layer of nickel which then iselectroplated with copper, after which the mold with its nickel andcopper deposits is withdrawn from the tank and the mold stripped fromthe plates. The plates, now consistin of nickel and copper, are turnedwith the copper surface up and a layer of an alloy of lead, tin andantimony is cast thereon.

An object of the present invention is to provide a method of recoveringsubstantially pure metallic nickel in powdered form from a plate orother article havin layers of nickel and copper thereon.

Still another object of the invention is to provide a method wherein thenickel may be stripped from theplatesor other nickel and copper-platedarticles in a relatively short length of time, purified and deposited asa finely divided powder which. is suitable for the production of nickelelectrodes of sufficient purity to be used in nickelplating operations.

With these and other objects in view, the invention consists in certainnew and novel methods and steps in the process of recovery as will behereinafter more fully described and pointed out i in the claims.

In the drawings,

Figure 1 is a fragmentary section of a plate from which the nickel is tobe recovered;

Figure 2 diagrammatically shows the steps in the recovery;

Figure- 3' diagramatically shows the electrolytic tank when. arranged.for the deposition of powderedniokelon suitable cathodes;

Figure 4': diagrammatically illustrates the compressing of the powderinto the form of an anode, and

Figure 5 is the anode in its completed form.

It will be understood that only that much of a flow sheet ordiagrammatic views are set out as is thought necessary to illustrate thepractice of the invention.

As heretofore mentioned, printing plates A are generally made up of anickel shell or plate I which was originally electrolytically depositedon a mold on which there has been formed an imprint by the originalcopper etching plate.

Electrolytically deposited on this nickel is the copper plated. shell 2while on the rear of this plate for tinning purposes and not shown inthe present view is a layer of tin for bonding the copper shell to thebase metal 3, which consists of electrotype metal made up of an alloy oflead, tin and antimony.

The plates A are sometimes in a curved form, rather than flat, as shown,but as pointed out in Patent No, 2,356,329 (the companion application)heretofore referred to, the plates may be flattened before being treatedfor the recovery of the nickel, copper. and the base metal-that is, thelead, tin and antimony.

As also mentioned in the Patent No. 2,356,329, before the electrolytetreatment of the plates is begun, they are thoroughly washed. in ahydrocarbon, such as kerosene, to remove the ink and other impurities,and a tank 4 for this purpose is shown in Figure 2 of the drawings. Theplates A may, of course, be brushed with a stiff metal ire brush afterbeing dipped in the washing tanks. They should then be cleaned with asolvent, such. as hot, soapy water.

After all the ink and impurities have been removed from the plates A,they are supported by hangers in a tank 5 which contains an electrolyticstripping solution, and the tank may be provided with stainless steelcathodes t which cooperate with the plates A that form the anodes. Aneconomical size tank is one that will hold 450. gallons and can besuccessfully operated by two men. A tank of the size mentioned will holdabout twenty-eight plates.

The stripping solution may consist of a 10% to 25% solution of muriaticacid, I-ICl, preferably about a 10% solution, containing about 3 ouncesof boric acid per gallon of solution inasmuch as this bath removes thenickel from the plates quicker than other baths containing HCl undersimilar conditions of temperature and current density. Good results areobtained, however, with stripping baths containing as little as 3%hydrochloric acid or as much as 25% hydrochloric acid. Also, the.quantity of boric acid can be varied considerably; for example, betweenabout 2 ounces per gallon and 5 ounces per gallon.

The boric acid acts as a lender medium to control the pH value of thesolution. Other suit able buffer mediums such as citric acid, aceticacid and sulfuric acid may be used, but I have obtained verysatisfactory results with boric acid.

The electric current may be of three to four volts with a maximum of4.00 amperes, and I have found that under ordinary conditions the nickelmay be'stripped from the plates A in four minutes or less. Under idealconditions the nickel canbe stripped from the plates in about fifteenseconds.

After the nickelhas been stripped from the platesfthey are washed underrunning water to remove all traces of the solution.

The corners of the plates, which were not subjected to the strippingaction, may be sheared off and the nickel also removed from theseshearings. The remaining plate, that is, the copper with its backing oflead, antimony and tin, is then subjected to the process set forth inthe Patent No. 2,356,329 to recover the copper and form the same-intoanodes and to also recover the base metal.

Referring again to the ist of the present in vention, it will beunderstood that since the tank 5 is of about 450 gallon capacity, it cancontain approximately 1000 pounds of nickel. Dueto the great solubilityof the nickel chloride, high concentrations of nickel may be built up inthe stripping tank, for example as much as 36 ouncesto the gallon.

Before the nickel is plated out of the solution, the solution orelectrolyte in the tank 5 must be treated with a hydrogen sulfide gas,ammonium sulfide or any equivalent reagent, which precipitates all thecopper, lead, tin and antimony as sulfides but leaves the nickel in theacid solution as nickel chloride. Ammonium sulfide may be introducedinto the bath in a plurality of streams and mixed with the bath. The pHvalue of the bath should not exceed 4 in order to avoid precipitation ofnickel sulfide.

If hydrogen sulfide is used, I provide a pipe 8 provided with theapertures 9 which connects with a blower In to bubble or force thehydrogen sulfide gas through the solution. This is necessary as in thestripping of the nickel from the plate thereis a small amount of lead,copper, tin andv antimony which will enter the solution and must beremoved.

The stripping solution may be treated with this hydrogen sulfide gas orother sulfide reagent at least once every week, and the solutionfiltered thus removing as sulfides all undesirable ions such as copper,lead, tin and antimony.

The duration of the treatment of the solution and the quantity ofsulfide reagent required to precipitate the impurities from the solutioncan be determined by removing a sample from the tank and filtering toobtain a clear solution. If hydrogen sulfide is then passed through orother suitable sulfide reagent is added to this clear, filtered sampleand no further precipitation takes place, all the undesirable metallicions have been precipitated. It must be made certain that the strippingsolution is acid before the hydrogen sulfide is introduced. Loss ofnickel as nickel sulfide is avoided by maintaining the bath of a pHvalue of 4 or lower.

After all the copper, lead, tin and antimony have been precipitated assulfides, the solution should be heated to about 150 F. and filtered,after which the filtrate is boiled to drive off any excess hydrogensulfide.

' Powdered nickel is deposited from the bath in the following way. Aplurality of carbon electrodes C are placed in the hangers previouslyused for supporting the plates A during the stripping operation and thestainless steel cathodes 6 are provided with pervious bags I which arenot attacked by the bath. The bags 1 are used to catch any of thedeposited powdered nickel that may drop from the electrodes 6.

The nickel may be deposited at a suitable cur rent density, dependinupon the type of the deposit desired. Powdered nickel can be depositedat a current density of about 3 to 5 amperes per square inch and atemperature of about 68 to 75 F. Such a high current density is used toprevent the deposition of a bright nickel plate which is deposited at acurrent density of about .2 to .3 ampere per square inch.

After the nickel has been deposited on the cathodes 6, they are removedfrom the tank 5, the recovered nickel is scraped from the cathodes,removed from the bags, washed and dried and made ready for the nextoperation. The recovere-d nickel is in the form of a, very finelydivided black magnetic powder.

If the nickel powder is to be formed into anodes, the powder is placedin the chamber or barrel of a press H and is subjected to a pressure offrom between eight to fifty tons per square inch, so that the nickel isnow compressed into a solid anode l2.

It will be understood that the shape or form of the anode l2 may be asdesired.

Finally, it will be understood that though I specifically stress thatthe nickel is reclaimed from printing press plates, the nickel might bereclaimed from other metal objects of a similar nature wherein there isa quantity of nickel to be recovered.

From the foregoing it will be seen that I first procure or strip thenickel from printing plates or similar objects which have heretoforebeen discarded for scrap, and then recover the nickel in its powderedform and subject the same to a great pressure to form anodes that givesuperior results to the rolled nickel anodes now in general use.

Having thus described my invention, what I claim as new and desired tosecure by Letters Patent is:

1. The method of forming nickel powder from printing plates, whichconsist of a layer of nickel, an underlying layer of copper and a baseformed of an alloy of lead, antimony and tin underlying said copperlayer, which consists in cleaning the plates; placing the plates in anelectrolytic bath consisting of between about a 3% and 25% hydrochloricacid solution and containing between about 3 and 5 ounces of boric acidper gallon; electrolytically stripping the nickel from the plate as ananode; thereafter precipitating copper, tin, lead and antimony ions assulfide compounds from said bath by introducing into said bath a fluidsulfide while maintaining the bath at a pH value lower than 4;separating the precipitated sulfide compounds from the acid electrolyticbath; and electrolytically depositing the nickel in powder form on acathode from said acid electrolytic bath.

2. A method of forming nickel powder from printing plates which platesare made of a layer of nickel, an underlying layer of copper and a baseformed of an alloy of lead, tin and antimony underlying said copperlayer which consists in thoroughly cleansing the p1ates;= placing theplates in anel'ectrolytic bath consisting essentially of a 3% to 25%hydrochloric acid solution containing a buffering agent;electrolytically stripping the nickel from the plates as anodes; passinghydrogen sulfide through the acid electrolytic bath to precipitate allthe metals except the nickel while maintaining the pH value at a pHvalue not exceeding 4; heating and filtering said electrolytic bath toobtain an acid solution of nickel chloride; and electrolyticallydepositing nickel on on de from said acid solution at a current densitybetween about 3 and 5 amperes per square inch to form nickel powder.

3. A method of forming nickel powder from printing plates which platesare made of a layer of nickel, an underlying layer or copper and asupporting base formed of an alloy of lead, tin and antimony underlyingsaid copper layer which consists in thoroughly washing the plates,placing the plates in an acid electrolytic bath consisting of about a10% solution oi" hydrochloric acid containing about 3 ounces of boricacid per gallon of solution, keeping the bath at about room temperature,passing a current of sufficient density through the bath to strip thenickel from the plate as an anode; passing hydrogen sulfide through theacid electrolytic bath to precipitate the copper and other ions; heatingthe acid electrolytic bath to approximately 150 F., filtering the same;and electrolytically depositing the nickel as a powder from saidfiltrate on a cathode at a current density between about 3 and 5 amperesper square inch.

4. The method of forming nickel powder from printing plates which platesare made up of a layer of nickel, an underlying layer of copper, and asupporting base formed of an alloy of lead, antimony and tin underlyingsaid copper layer, which consists in thoroughly cleansing the plates,placing the plates as anodes in an electrolytic bath consisting of about10% hydrochloric acid containing about 3 to 5 ounces of boric acid pergallon of acid solution, passing a current through the bath of suficientdensity to strip the nickel from the plates, together with a"smallamount of other metallic ions; removing the plates; passing hydrogensulfide through the acid bath to precipitate sulfides of the metalsother than nickel while maintaining the latter at a pH value of not morethan about 4; heating the bath to approximately 159 F., filtering thesame; and passing a current at a density between about 3 and 5 amperesper square inch therethrough to deposit the nickel in powder form on thecathode.

5. A method of forming nickel powder from articles having a layer ofnickel superimposed on a layer of copper comprising immersing saidarticles in an electrolytic bath consisting of about a 3% to 25%solution of hydrochloric acid containing a buffering agent,electrolytically stripping said nickel layer and some of said copperfrom said article, removing said article from said bath, precipitatingthe stripped copper from said bath as cop-per sulfide at a pH value notexceeding 4 to avoid formation of nickel sulfide by introducing intosaid bath a fluid sulfide, and depositing nickel from said acid solutionon a cathode at a current density between about 3 and 5 amperes persquare inch to deposit the nickel as a powder.

AXEL E. LUNDBYE.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Name Date Wells et al. July 15, 1913 Ballard Apr.25, 1939 Blaut May 7, 1940 Mantell Feb. 25, 1941 FOREIGN PATENTS CountryDate Great Britain 1929 Australia 1940 OTHER REFERENCES Number Number

